VLF transmitters and receivers require very long antennas to transmit properly and operating at such frequencies is not a good choice at all unless you happen to be a nuclear powered submarine looking to receive missile launch orders while still submerged.

well it is going to be submerged ! and it is going to receive and send text ! but not more than a Km and not more that 100 m depth ! ALSO ! financially i am not able to buy a VW beatle, for sure not a Nuclear submarine XD ! but thank you anyway !